Something to keep in mind is that backing up the files on disk and the database are two separate processes. This means that it's possible that your metadata and filesystem could get out of sync. It's not an insurmountable issue, but it's one to be aware of. The worse that can happen is that you have pages for which there are not documents, and vice versa. The closer you can keep the backups in sync, the better.
Our database is backed up every hour, and we take diffs of the file system every hour. In a recovery scenario, we'll take the newest set that enables us to restore the file system and apply transaction logs to match. If the database has a more recent backup, we'll check to see which documents have no pages, and use that information to know what we possibly lost. We don't mind documents with no pages, but we'd like to avoid pages sitting out there with no matching documents.